The present invention relates to containers for radiation-sensitive material, and more particularly to improvements in containers for X-ray films or the like. Still more particularly, the invention relates to improvements in devices for confining sheets or panels of X-ray film or the like between two spaced-apart layers in such a way that the film contacts at least one stratum of fluorescent material.
It is already known to confine a sheet or panel of X-ray film between two rigid or flexible walls which form part of a cassette or an analogous container. A known cassette which has rigid walls and serves for confinement of X-ray film includes intensifying foils which are biased against the film by inserts consisting of foamed synthetic plastic material. Such inserts are applied to the inner side or sides of one or both rigid walls. A cassette with flexible walls is disclosed, for example, in German Auslegeschrift No. 12 21 548, wherein the film and the intensifying foils are confined in a deformable (flexible) envelope or wrapper consisting of a material which is permeable to X-rays. The intensifying foils are caused to bear against the respective sides of the film in response to evacuation of air from the interior of the envelope.
Commonly owned allowed copending application Ser. No. 4,308 filed Jan. 17, 1979 by Walter Bauer discloses means for uniformizing the pressure which the intensifying foils apply to the film. To this end, the container comprises a magnetic plate which cooperates with a second plate consisting of ferromagnetic material. The sandwich including the film and two intensifying foils which flank the film is interposed between the two plates whereby the magnetic plate attracts the ferromagnetic plate and thereby urges the foils against the respective sides of the film. Owing to the provision of numerous layers and carriers for such layers, the distance between the film and the object or objects to be examined is quite pronounced. This reduces the sharpness of the image. Moreover, the magnetic plate must be relatively thick in order to ensure adequate attraction of the ferromagnetic plate. As is known, magnetic attraction between the two plates decreases proportionally with the square of the distance therebetween.